Cassius and Ceraunus Blue Butterfly Eggs and Caterpillars; How to Find Them in Your Yard

Continuing to answer the question about finding eggs and caterpillars in one's yard, we move to Cassius Blue and Ceraunus Blue butterflies. Both are beautiful little butterflies. The males are brilliant blue on the inside of their wings. The females have less blue.

Ceraunus Blue butterfly, first photo. Cassius Blue butterfly, second photo.

Marc and Maria Minno, in their book Florida Butterfly Gardening, share a tip to find these caterpillars. Simply gather flower buds of their host plants, place the buds in a plastic container, and check for frass (caterpillar excrement) the next day. If there is frass, there is a caterpillar!

Eggs of the Ceraunus Blue butterfly are pale blue and will be found on Hairy Indigo and other Indigofera sp plants. Eggs of the Cassius Blue butterfly are cream/white and will be found on the flower buds of Leadwort (Plumbago sp) plants.

The green caterpillar blends in with the flower buds so well that it is nearly impossible to see these tiny caterpillars. Fully grown and ready to pupate, they may be as large as one inch long. An intense study of the flower buds can still fail to reveal the caterpillar.


Once flower buds of the host plant are placed into a plastic container, wait one day. If frass is evident the next day, you know a caterpillar is also in the container.

The paper towel was added to absorb moisture from the flower buds.

Happy Hunting!